Various (phenoxyphenoxy)propionate compounds are known to possess herbicidal and plant-growth regulating properties. For example, see U.S. Pat. Nos. 3,954,442; 4,550,192; 4,332,961; 4,332,960; 4,370,489; 4,276,080 and British Patent Specification 1,577,181. Also, methods for preparing enantiomers are described in U.S. Pat. Nos. 4,531,969 and 4,532,328. In U.S. Pat. No. 4,252,980 a method is taught for preparing the methyl ester.
Of particular interest among the (phenoxyphenoxy)propionate herbicides are the 2-(4-(2'-halo-4'-bromophenoxy)phenoxy)propionates which exhibit particularly desirable properties as described in U.S. Pat. Nos. 4,370,489: 4,531,969; and 4,550,192.
Processes for making selected intermediates used to prepare (phenoxyphenoxy)propionates are taught in U.S. Pat. Nos. 3,721,703; 4,238,626; 4,252,980; 4,301,295: 4,309,547 and 4,391,995. Although these processes are effective, a number of them utilize diazonium reactions which are potentially explosive when employed on an industrial scale. It is desirable to find methods for preparing phenoxyphenoxy compounds which are as safe as or safer than those previously taught. It is also desirable to find a method which employs a fewer number of steps than other known processes. It is also desirable to find methods where yields are as good as or better than previously known processes.